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xdp: introduce xdp_return_frame_rx_napi

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When sending an xdp_frame through xdp_do_redirect call, then error
cases can happen where the xdp_frame needs to be dropped, and
returning an -errno code isn't sufficient/possible any-longer
(e.g. for cpumap case). This is already fully supported, by simply
calling xdp_return_frame.

This patch is an optimization, which provides xdp_return_frame_rx_napi,
which is a faster variant for these error cases.  It take advantage of
the protection provided by XDP RX running under NAPI protection.

This change is mostly relevant for drivers using the page_pool
allocator as it can take advantage of this. (Tested with mlx5).

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jesper Dangaard Brouer 2018-05-24 16:46:07 +02:00 committed by Alexei Starovoitov
parent 9940fbf633
commit 389ab7f01a
5 changed files with 22 additions and 8 deletions
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5
include/net/page_pool.h
View file

@ -115,13 +115,14 @@ void page_pool_destroy(struct page_pool *pool);
void __page_pool_put_page(struct page_pool *pool,
struct page *page, bool allow_direct);
static inline void page_pool_put_page(struct page_pool *pool, struct page *page)
static inline void page_pool_put_page(struct page_pool *pool,
struct page *page, bool allow_direct)
{
/* When page_pool isn't compiled-in, net/core/xdp.c doesn't
* allow registering MEM_TYPE_PAGE_POOL, but shield linker.
*/
#ifdef CONFIG_PAGE_POOL
__page_pool_put_page(pool, page, false);
__page_pool_put_page(pool, page, allow_direct);
#endif
}
/* Very limited use-cases allow recycle direct */

1
include/net/xdp.h
View file

@ -104,6 +104,7 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
}
void xdp_return_frame(struct xdp_frame *xdpf);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
void xdp_return_buff(struct xdp_buff *xdp);
int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,

2
kernel/bpf/cpumap.c
View file

@ -578,7 +578,7 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
err = __ptr_ring_produce(q, xdpf);
if (err) {
drops++;
xdp_return_frame(xdpf);
xdp_return_frame_rx_napi(xdpf);
}
processed++;
}

2
kernel/bpf/devmap.c
View file

@ -239,7 +239,7 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
err = dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);
if (err) {
drops++;
xdp_return_frame(xdpf);
xdp_return_frame_rx_napi(xdpf);
} else {
sent++;
}

20
net/core/xdp.c
View file

@ -308,7 +308,13 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
static void xdp_return(void *data, struct xdp_mem_info *mem)
/* XDP RX runs under NAPI protection, and in different delivery error
* scenarios (e.g. queue full), it is possible to return the xdp_frame
* while still leveraging this protection. The @napi_direct boolian
* is used for those calls sites. Thus, allowing for faster recycling
* of xdp_frames/pages in those cases.
*/
static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct)
{
struct xdp_mem_allocator *xa;
struct page *page;
@ -320,7 +326,7 @@ static void xdp_return(void *data, struct xdp_mem_info *mem)
xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
page = virt_to_head_page(data);
if (xa)
page_pool_put_page(xa->page_pool, page);
page_pool_put_page(xa->page_pool, page, napi_direct);
else
put_page(page);
rcu_read_unlock();
@ -340,12 +346,18 @@ static void xdp_return(void *data, struct xdp_mem_info *mem)
void xdp_return_frame(struct xdp_frame *xdpf)
{
xdp_return(xdpf->data, &xdpf->mem);
__xdp_return(xdpf->data, &xdpf->mem, false);
}
EXPORT_SYMBOL_GPL(xdp_return_frame);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
{
__xdp_return(xdpf->data, &xdpf->mem, true);
}
EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
void xdp_return_buff(struct xdp_buff *xdp)
{
xdp_return(xdp->data, &xdp->rxq->mem);
__xdp_return(xdp->data, &xdp->rxq->mem, true);
}
EXPORT_SYMBOL_GPL(xdp_return_buff);